<p>Checks that a source file begins with a specified header. Property headerFile specifies a file that contains the required header. Alternatively, the header specification can be set directly in the header property without the need for an external file.</p>
<p>Property ignoreLines specifies the line numbers to ignore when matching lines in a header file. This property is very useful for supporting headers that contain copyright dates. For example, consider the following header:</p>
<pre>
    line 1: ////////////////////////////////////////////////////////////////////
    line 2: // checkstyle:
    line 3: // Checks Java source code for adherence to a set of rules.
    line 4: // Copyright (C) 2002  Oliver Burn
    line 5: ////////////////////////////////////////////////////////////////////
</pre>
<p>Since the year information will change over time, you can tell Checkstyle to ignore line 4 by setting property ignoreLines to 4.</p>